fix: Add info about Dev Portal homepage slugs

Jobs to be done (optional)

It's unclear to customers how to make a Dev Portal homepage via the API or Terraform (in the UI, this is created for them by default). When they try to make one, like /home, it gives them a 404.

Definition of done

• Document that they need to create a / page (if they're using the API or TF) to create a home page here https://developer.konghq.com/dev-portal/apis/#page-structure
• Update the page creation steps here and here so that they create a homepage with / as well as the already documented /apis page with a sentence that describes that this is creating a homepage for them as well as a page for their apis.

Information

Slack feedback: https://kongstrong.slack.com/archives/CDSTDSG9J/p1756386574049769

Due date (optional)

N/A

Size

Small

Start with the linked Dev Portal page-structure documentation and the Dev Portal sections in the API Catalog and Terraform automation guides. Locate their source files, document that / creates the homepage, and update both creation walkthroughs to create / alongside /apis; done when all three linked pages explain the homepage behavior.